The present invention relates to a telltale element adapted to be secured to an article to be maintained under surveillance.
In U.S. Pat. No. 3,895,368, issued July 15, 1975, for "Surveillance System and Method Utilizing Both Electrostatic and Electromagnetic Fields" and assigned to the same assignee as the present application, there is described a system wherein a microwave signal generator projects an electromagnetic wave into a space under surveillance to establish a first field. A pulse or frequency modulated low frequency generator is used to apply a voltage to a discontinuous conductor for establishing a second field, electrostatic in nature, throughout the space. Presence in the space of a miniature passive electromagnetic wave receptor-reradiator in the form of a semiconductive diode connected to a dipole antenna causes the reradiation of a low frequency component modulated on a microwave component as a carrier. The front end of a receiver system is tuned to the microwave frequency and feeds a suitable detector circuit responsive to the low frequency signal. A coincidence circuit energizes an alarm circuit whenever the detected signal coincides with the original modulation envelope being applied to the low frequency generator.
In U.S. Pat. No. 4,139,844, issued Feb. 13, 1979, for "Surveillance Method and System with Electromagnetic Carrier and Plural Range Limiting Signals" and assigned to the same assignee as the present application, there is described an improved surveillance system wherein two low frequency signals are radiated into the surveillance field from opposite sides to limit the field size in addition to the microwave carrier signal transmitted throughout such field. The miniature receptor-reradiator responds to the signals when in the field to return a modulated carrier signal to a receiver device for actuating an alarm. The alarm is actuated only when the receiver detects a signal having a carrier component corresponding to the microwave signal with sideband components corresponding to the sum of the frequencies of the two low frequency signals.
Reusable security tags adapted to operate in the foregoing systems have been disclosed and claimed in U.S. Pat. No. 3,942,829, issued Mar. 9, 1976, entitled "Reusable Security Tag" and U.S. Pat. No. 4,299,870, issued Nov. 10, 1981, entitled "Reusable Theft Deterrent Security Tag", both of which are assigned to the same assignee as the present invention. Such patents disclose the construction of enclosures or housings for the telltale element providing for the fastening of such elements to garments or similar articles of merchandise. Thus, in U.S. Pat. No. 3,942,829 there is disclosed a reusable security tag having an enclosure containing an element detectable by independent means and a cruciate sheet metal clutch lock. A pin for piercing a garment is secured at the end of a lever arm which is hinged to said enclosure for controlled movement into said lock. Said pin is released from said clutch lock by application of a special tool to said enclosure for deforming the clutch to spread its jaws. U.S. Pat. No. 4,299,870 discloses an improved construction of the enclosure.
The enclosure disclosed in U.S. Pat. No. 3,942,829 had an overall length of approximately 41/2 inches and a width of about 1 7/32 inches. The improved enclosure disclosed and claimed in U.S. Pat. No. 4,299,870 effected a slight reduction in size having an overall length of about 4 3/16 inches and a width throughout most of its length of about 7/8 inches. Reference to the last mentioned patent will reveal that the enclosure had a pair of opposing wings to be engaged by a releasing tool which wings increased the width of the enclosure to about 1 1/16 inches. While such tags have served admirably in actual use, there has developed a need for a smaller lighter weight tag and it is to that end that the present invention addresses itself.